The invention relates to a sealing diaphragm (1) and a check valve (9) comprising a sealing diaphragm (1) for fluid technology applications. A sealing diaphragm (1) for fluid technology applications is to be provided, which is economical and constructionally simple to produce, which can be used as a closing means for a check valve (9) and with which unwanted interfering noise can be prevented during operation. The object of the invention is achieved by a sealing diaphragm (1) with a flat, flexible sealing section, which can be bent or curved with a fluid pressure, wherein at least one resilient frictional tooth (4) is provided on or next to the surface of the sealing section at a distance from an edge of the sealing section, designed and arranged in such a way that it forms an angle between 30 degrees and 150 degrees with the sealing section and it tilts together with the bending or curving movement of the flat sealing section, wherein the frictional tooth has a contact surface (7) on a side orientated in the tilting direction. The object of the invention is also achieved by a check valve (9) for fluid technology outlet openings, comprising a housing part (10) having a fluid outlet (12), wherein an above-mentioned sealing diaphragm (1) is arranged in the flow path of the outlet opening, which is in contact with a sealing surface of a seal seat with a sealing section against the direction of flow and which can be bent or curved with a fluid pressure in the flow direction, wherein the contact surface (7) of the at least one frictional tooth (4) is simultaneously in contact with a corresponding bearing surface.